A-body vs fmj spindle for handling?

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fishmarket

fishmarket

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I posted this question on moparts as well but I’m curious to hear what the a-body folks think on the subject. Just curious what everyone’s take is on the a-body vs Fmj spindle in a handling application? It seems as though the fmj spindle is not only lighter but has better “numbers” than the a-body counterpart with the exception of have a higher roll center and slightly worse toe change on extreme extension. I’m personally building an a-body and an e-body with handling in mind and have both sets of knuckles to chose from. Which should I use?
 
Splittin hairs. Just use them for disc brakes and have at it.
 
An FMJ spindle isn't any "lighter" than an A body one.
Never heard that before.
Then how many ounces would it amount to, anyway?
 
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I have FMJs on my road runner, didn't notice any handling difference at all from the stock 11x3 drum spindles, just better brakes.
 
bigblockdart.com has an extensive analysis of the 3/8" difference in height and how it does or does not affect the rest of the suspension.
 
YY1 said:
bigblockdart.com has an extensive analysis of the 3/8" difference in height and how it does or does not affect the rest of the suspension.
Click to expand...


I’ve read this multiple times over. That’s where some of my information came from. Just wondering if anyone here that has a car that is made to handle has any actual seat of the pants information.
 
hemi71x said:
Well i don't believe that.
That "editor" doesn't know what he talks about in lots of instances.
Weigh them yourself and see, if you have both styles, in your inventory of parts.
Click to expand...

Great idea! Thanks for your help!
I’m not home for the next few days but I will weigh them when I get home. In the meantime, here is a link to the original article in hot rod magazine. Picture 3 of 10 explains the 3lb difference and you can clearly see the contoured back and extra material that is removed compared to the a-body spindle. Bill Reilly from Reilly Motorsport is the author.

Swapping Disc-Brake Spindles - Mopar Muscle Magazine
 
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We put the FMJ spindles on my son's Barracuda, mainly due to Bill Reilly's analysis. Never got back to the autocross track after the change, though. He did do quite a bit street driving on them without issue.
AlanLuskCuda.jpg
 
Kern Dog said:
That car looks tough with those NASCAR huge tires on it!
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Thanks. We liked it. My wife and went to Mesa Marin raceway in Bakersfield one afternoon and they let us take any used tire we wanted out of their scrap pile for free. Came home with 28 tires (some with zero treadwear) and raced a season and a half on them. Still had some good ones when we were no longer racing the car. We made up the 15x10 wheels with fresh rims and old small bolt centers with the exact offset that we needed. When we broke a center we switched to big bolt, sold a good pair of small bolt 15x10s, built a pair of 15x10 rallyes from some 14s and bought two Pete Paulsen circle track wheels for about the same price as the outer rims. All we have left are the two Paulsen rims with some dead tires on them. Now the car sits for time when my son can rebuild it.
 
I have always liked the look of a car with wide tires at all four corners. The NASCAR look appealed to me far more that the drag race look with pizza cutter front tires.
 
Jim Lusk said:
We put the FMJ spindles on my son's Barracuda, mainly due to Bill Reilly's analysis. Never got back to the autocross track after the change, though. He did do quite a bit street driving on them without issue.View attachment 1715386019
Click to expand...
I bet that front end has alot of modifications sheet metal wise to fit those tires.
Great pic
 
sireland67 said:
I bet that front end has alot of modifications sheet metal wise to fit those tires.
Great pic
Click to expand...

Only opening the wheel openings. The car was a used up drag car that had already been cut on when we dragged it home as a parts car. Due to issues with the other '67 fastback we figured we would put the drive train in (383/4sp/3.55SG) so that my son would have a fun car his senior year of high school. We were originally autocrossing on decent street tires and then got hooked up with a local contact for the NASCAR slicks. That dried up so we headed to Bakersfield. So, we cut it some more.
 
fishmarket said:
Great idea! Thanks for your help!
I’m not home for the next few days but I will weigh them when I get home. In the meantime, here is a link to the original article in hot rod magazine. Picture 3 of 10 explains the 3lb difference and you can clearly see the contoured back and extra material that is removed compared to the a-body spindle. Bill Reilly from Reilly Motorsport is the author.

Swapping Disc-Brake Spindles - Mopar Muscle Magazine
Click to expand...


if bill said there was 3 pounds difference between the two then i'm sure he weighed them and there i three pounds difference between the ones he had in the article...
 
fishmarket said:
Great idea! Thanks for your help!
I’m not home for the next few days but I will weigh them when I get home. In the meantime, here is a link to the original article in hot rod magazine. Picture 3 of 10 explains the 3lb difference and you can clearly see the contoured back and extra material that is removed compared to the a-body spindle. Bill Reilly from Reilly Motorsport is the author.

Swapping Disc-Brake Spindles - Mopar Muscle Magazine
Click to expand...

Given the choice, I'd take the 3 pounds if it makes them stronger.
That's my 2 cents.
How much does two pennies weigh?
 
YY1 said:
bigblockdart.com has an extensive analysis of the 3/8" difference in height and how it does or does not affect the rest of the suspension.
Click to expand...
I’m not sure if a camber change chart from 20 yrs ago qualifies as extensive analysis, but if memory serves, the camber curve and the roll center height are both worse than the A spindle.
 
hemi71x said:
Well i don't believe that.
That "editor" doesn't know what he talks about in lots of instances.
Weigh them yourself and see, if you have both styles, in your inventory of parts.
Click to expand...
If you disagree and try to express that, it is on YOU to provide evidence that you are right. Until then, I'm going to trust people that have a reputation in the hobby outside of selling used parts on web forums.
 
GMachineDartGT said:
I’m not sure if a camber change chart from 20 yrs ago qualifies as extensive analysis, but if memory serves, the camber curve and the roll center height are both worse than the A spindle.
Click to expand...

Worse than "what"? So the a body spindles are somehow "bad"? my big old butt.
 
GMachineDartGT said:
A body spindle is better than the fmj in these qualities
Click to expand...

What "qualities"? Seems to me the A body spindles were pretty darn good enough to win the first seven places in the NASCAR compact car series in 1960. I think it's splittin hairs at best. Spreading incorrect info at worst. Without plotted graphs of camber, caster, SAI and included angles, there's no way I would advise one against the other.
 
I think that Peter is referring to the 73-76 A body disc knuckle.
I read the Debated Usage article and remember some of the details. If I recall, the FMJ had a larger amount of camber gain through the range of travel but also a larger amount of toe change.
I like camber gain. Toe change...not so much.
 
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